<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title></title>
</head>
<body>
<script type="text/javascript">
  var obj = {}
  obj = null 

  function fn () {
    var a = 3
    //debugger
  }
  fn();
  debugger
</script>
</body>
</html>